This invention generally relates to a method and apparatus for increasing pedestrian safety near vehicles by connecting object detector sensors located at the front or rear of a vehicle to vehicle antilock braking systems, traction control systems or engine controls with appropriate circuitry to prevent vehicle motion when a pedestrian is present.
According to the National Highway Transportation Safety Administration, pedestrian fatalities while loading and unloading school buses account for approximately three times as many fatalities as when the passengers are on board the bus. Younger children are particularly vulnerable to fatal pedestrian school bus accidents according to the Transportation Research Board.
In response to this problem, various operational procedures, such as safety training of children and the addition of monitors to the bus crew have been implemented. While these precautions are partially effective, the restricted visibility at the immediate front and rear of buses which transport young children continues to expose errant children to a potential hazard when they walk into a position where the drivers vision is obscured. Despite these operational safeguards, there is still a yearly death toll because children alight from the bus and proceed into an obscured area, particularly in the xe2x80x9cdanger zonesxe2x80x9d directly in front of or to the rear of the bus.
Another response to school bus loading and unloading fatalities is the use of crossing control arms exemplified by U. S. Pat. No. 4,697,541. A crossing arm unit consists of a frame attached to the front bumper of a bus and an arm pivotally mounted to the frame which swings out from the bumper to provide a gate for the purpose of guiding children away from the front of the bus. Typically, a motor, slip clutch, switches and controls actuate such control arms.
There are a number of known disadvantages to these units. The foremost is that a child may simply walk around the arm, in which case the arm may even create a false sense of security in the driver. The arm is fundamentally a passive safety system which depends on the behavior of the children for effectiveness. To prevent evasion of the arm, U.S. Pat. Nos. 5,564,359 and 5,620,219 describe complex safety systems with two arms connected by a cable or band which open into a rectangular cordon in front of the bus.
The arm itself is a vulnerable projection from the vehicle when deployed, subject to being struck and damaged by other vehicles. The actuation motor and controls are in an extreme environment on the lower front of the vehicle and corrosion of motors, wiring connections and sensors is common. Furthermore the arm itself swings out and can strike a pedestrian, necessitating the slip clutch to prevent striking a substantial blow.
Crossing control arms are required in 18 states, representing 37% of the United States population. While the trend in loading zone fatalities over the past 10 years has generally been downward and there is some evidence that crossing arms have contributed to this decline, the latest data from the Kansas State Department of Education""s nationwide School Bus Loading and Unloading Zone Survey calls the effectiveness of crossing arms into question and points to the need for additional effective safety measures. For the 1998-99 school year loading fatalities rose significantly and the 36% of states requiring crossing arms accounted for a disproportionate 66% of the fatalities. Furthermore, this same study points out that over the past ten years between ⅓ and xc2xd of the fatalities occur at the rear of the bus, an aspect of loading zone safety which crossing control arms do not address.
A different approach to improving loading zone safety which is applicable to both the front and rear of a vehicle are electronic proximity sensors. Proximity sensors capable of detecting a human presence adjacent to a vehicle are well known in the art using methods such as radar, ultrasonics and electo-optics. Typical applications of such sensors for the detection of other vehicles while moving are found in U.S. Pat. Nos. 4,015,232, and 4,766,421. U.S. Pat. No. 5,160,927 describes an ultrasonic system apparently intended to provide a warning while the vehicle is either stationary or mobile. Sensors of these types have the inherent reliability and self-test advantages of a solid-state electronic device when compared to a mechanical crossing control arm. A combination of both a crossing control arm and a proximity sensor is described in U.S. Pat. No. 5,132,662 which coordinates the actions of both safety systems to detect a child that has evaded the arm.
What is notable about the prior sensor art is that each device provides only a warning, either audible or visual, upon which the driver must act. Thus, similar to a crossing control arm, sensor based detection of a pedestrian in the proximity of a vehicle is a passive system, dependent on further action from the driver to prevent injury to the child.
Modern automotive vehicles employ a number of electronic control systems, such as antilock braking systems, traction control systems or engine controls with appropriate circuitry to control vehicle motion. Upon receiving a signal, these electronic control systems can be used individually or in concert to prevent vehicle movement by creating brake fluid pressure for applying the vehicle service brakes. For example, a traction control system can apply the brakes or limit the throttle position or an engine control can limit the engine output or stop the engine altogether.
Accordingly, this invention provides for a vehicle safety interlock system which prevents vehicle motion when an object, such as a child, is in the danger zones at the front or rear of the vehicle, overcoming the problems and disadvantages of the conventional techniques in the art. The invention further provides an active safety system for vehicles which functions automatically without depending on the driver or passengers for effectiveness and which uses existing vehicle electronic control systems.
Briefly, the invention includes an object detection sensor located at the front or rear of the vehicle which provides a signal upon the presence of a person in the potential path of movement of the vehicle when the vehicle is stopped, the signal being supplied to an existing electronic control module of the vehicle capable of preventing vehicle motion.
Further objects, features and advantages of the invention will become apparent from consideration of the following description and the appended claims when taken in connection with the accompanying drawings.